diff --git a/crates/dbx-mcp/src/backend.rs b/crates/dbx-mcp/src/backend.rs
index 705acfd041..b6ff7b79d2 100644
--- a/crates/dbx-mcp/src/backend.rs
+++ b/crates/dbx-mcp/src/backend.rs
@@ -587,7 +587,12 @@ impl LocalBackend {
     }
 
     pub async fn open(path: &Path) -> Result<Self, String> {
-        Self::open_with_app_version(path, env!("CARGO_PKG_VERSION")).await
+        // The standalone MCP binary and CLI are versioned independently from
+        // the DBX app, so their crate version must not stand in for the app
+        // version during plugin `engines.dbx` checks: a plugin requiring
+        // DBX >= 0.5.68 would be rejected against e.g. 0.4.90 (#9595). An
+        // empty version makes the compatibility check skip that requirement.
+        Self::open_with_app_version(path, "").await
     }
 
     /// Same as [`open`], but lets tests and embedded callers pin the app version
@@ -3828,6 +3833,43 @@ mod tests {
         assert_eq!(backend.state().agent_manager.base_dir(), &agent_dir);
     }
 
+    #[tokio::test]
+    async fn local_backend_standalone_open_skips_plugin_dbx_engine_gate() {
+        let data_dir = tempfile::tempdir().unwrap();
+        let database_path = data_dir.path().join("dbx.db");
+        let plugin_dir = data_dir.path().join("plugins").join("io.dbx.gated");
+        std::fs::create_dir_all(plugin_dir.join("ui")).unwrap();
+        std::fs::write(plugin_dir.join("ui").join("index.html"), "<!doctype html>").unwrap();
+        std::fs::write(
+            plugin_dir.join("manifest.json"),
+            r#"{
+                "manifest_version": 1,
+                "id": "io.dbx.gated",
+                "name": "Gated",
+                "version": "1.0.0",
+                "publisher": "example",
+                "engines": { "dbx": ">=999.0.0", "host_api": "^1.0" },
+                "entrypoints": { "ui": { "root": "ui", "entry": "ui/index.html" } },
+                "permissions": ["host.events"]
+            }"#,
+        )
+        .unwrap();
+        let storage = Storage::open(&database_path).await.unwrap();
+        drop(storage);
+
+        // The standalone host has no app version to compare against (#9595).
+        let backend = LocalBackend::open(&database_path).await.unwrap();
+        let installed = backend.state().plugins.list_installed().unwrap();
+        let plugin = installed.iter().find(|plugin| plugin.manifest.id == "io.dbx.gated").unwrap();
+        assert!(plugin.compatibility.compatible, "{:?}", plugin.compatibility.errors);
+
+        // A host that knows the app version keeps enforcing the requirement.
+        let backend = LocalBackend::open_with_app_version(&database_path, "0.6.16").await.unwrap();
+        let installed = backend.state().plugins.list_installed().unwrap();
+        let plugin = installed.iter().find(|plugin| plugin.manifest.id == "io.dbx.gated").unwrap();
+        assert!(!plugin.compatibility.compatible, "{:?}", plugin.compatibility.errors);
+    }
+
     #[test]
     fn local_plugin_directory_honors_desktop_storage_settings() {
         let data_dir = Path::new("C:/Users/user/AppData/Roaming/com.dbx.app");
diff --git a/crates/dbx-plugin-runtime/src/plugins/manifest.rs b/crates/dbx-plugin-runtime/src/plugins/manifest.rs
index a80df0f850..d42fa367f1 100644
--- a/crates/dbx-plugin-runtime/src/plugins/manifest.rs
+++ b/crates/dbx-plugin-runtime/src/plugins/manifest.rs
@@ -1009,6 +1009,13 @@ fn validate_engine_requirement(label: &str, requirement: &str, actual: &str, err
     if requirement.trim().is_empty() {
         return;
     }
+    // An empty installed version means the host could not identify itself (the
+    // standalone MCP binary and CLI are versioned independently from the DBX
+    // app). The requirement is unverifiable there, not unsatisfied, so skip it
+    // instead of failing every plugin (#9595).
+    if actual.trim().is_empty() {
+        return;
+    }
     let requirement = match VersionReq::parse(requirement.trim()) {
         Ok(requirement) => requirement,
         Err(error) => {
@@ -1608,6 +1615,34 @@ mod tests {
         assert_eq!(manifest.localizations["zh-CN"].name.as_deref(), Some("本地化插件"));
     }
 
+    #[test]
+    fn compatibility_skips_dbx_engine_gate_for_unknown_host_version() {
+        let dir = tempfile::tempdir().unwrap();
+        std::fs::create_dir_all(dir.path().join("ui")).unwrap();
+        std::fs::write(dir.path().join("ui").join("index.html"), "<!doctype html>").unwrap();
+        let manifest: PluginManifest = serde_json::from_value(serde_json::json!({
+            "manifest_version": 1,
+            "id": "io.dbx.example",
+            "name": "Example",
+            "version": "1.0.0",
+            "publisher": "example",
+            "engines": { "dbx": ">=999.0.0", "host_api": "^1.0" },
+            "entrypoints": { "ui": { "root": "ui", "entry": "ui/index.html" } },
+            "permissions": ["host.events"]
+        }))
+        .unwrap();
+
+        // A standalone host reports no app version: the requirement is
+        // unverifiable there, not unsatisfied (#9595).
+        let compatibility = manifest.compatibility(dir.path(), "");
+        assert!(compatibility.compatible, "{:?}", compatibility.errors);
+
+        // A host that knows the app version keeps enforcing the gate.
+        let compatibility = manifest.compatibility(dir.path(), "0.6.16");
+        assert!(!compatibility.compatible, "{:?}", compatibility.errors);
+        assert!(compatibility.errors.iter().any(|error| error.contains(">=999.0.0")), "{:?}", compatibility.errors);
+    }
+
     #[test]
     fn rejects_invalid_localization_metadata() {
         let dir = tempfile::tempdir().unwrap();